With social development, user's demand on storing data in embedded terminals such as cell phone, laptop computer has been increasingly growing. However, for reasons of cost, etc., it is not possible for embedded terminals to provide a storage space which fits demands of all users. In practice, small scale storage media such as MMC/SD storage card, Micro-SD storage card and Mini-SD storage card are usually used to provide expanded data space. Currently, it is already very common in embedded system field to use a MMC/SD interface to expand user-available storage space in those terminals. FIG. 1 shows a typical bulk storage structure model which is based on MMC/SD interface. The model comprises at least one master MMC/SD apparatus 101 and at least one slave MMC/SD apparatus 102 which are connected to each other via MMC/SD interface. As shown in FIG. 1, the master MMC/SD apparatus 101 comprises a master controller 103, a master bulk storage device 105, a master MMC/SD interface drive device 107 and a master MMC/SD interface, whereas the slave MMC/SD apparatus 102 comprises a slave controller 104, a slave bulk storage device 106, a slave MMC/SD interface drive device 108 and a slave MMC/SD interface. The master controller 103 uses the master bulk storage device 105 to provide file system service as well as management service for slave apparatus to store data, while the master MMC/SD interface drive device 107 is used to achieve transfer of MMC/SD signaling over MMC/SD interface. Similarly, the slave controller 104 is designed to control operation of the slave bulk storage device 106 and the slave MMC/SD interface drive device 108, and the slave controller 104 provides data storage service through the slave bulk storage device 106. The master apparatus and the slave apparatus may also comprise various general purpose or dedicated purpose peripheral devices (not shown in FIG. 1).
TCP/IP protocol based Ethernet is currently the most widely used local area network technology. Since Ethernet platform technology makes it easy to expand, simple for maintenance and convenient to build network, this technology has also continually extended into other embedded system fields. In embedded system fields, the physical layer interface of Ethernet mainly takes the form of PCI network card, USB card and optical fiber card, etc. Currently, MMC/SD interface can also be used as physical layer interface of Ethernet. FIG. 2 shows an Ethernet communication model which is based on MMC/SD interface in the prior art. The model also comprises at least one master MMC/SD apparatus 201 and at least one slave MMC/SD apparatus 202 which are connected to each other via MMC/SD interface. Unlike the bulk storage structure model shown in FIG. 1, the master MMC/SD apparatus 201 comprises a master communication protocol stack device 205 and does not comprise master bulk storage device. Similarly, the slave MMC/SD apparatus 202 comprises a slave communication protocol stack device 206 and does not comprise master bulk storage device. Both the master MMC/SD apparatus 201 and the slave MMC/SD apparatus 202 may comprise various general purpose or dedicated purpose peripheral devices. MMC/SD interface-based Ethernet communication system aims to expand network applicability of embedded terminal apparatus without changing hardware structure thereof.
However, MMC/SD interface-based embedded terminal apparatus in the prior art either solely supports a master bulk storage device, or solely supports a master communication protocol stack device. That is, if the users intends that the embedded terminal apparatus simultaneously supports bulk storage device and Ethernet communication, it is necessary that at least two MMC/SD interfaces be provided in the embedded terminal apparatus, and the user also has to hold at least two slave MMC/SD apparatus, i.e., one supports master bulk storage device only and the other supports master communication protocol stack device only. As a result, manufacture cost of embedded terminal apparatus is increased and many inconveniences have also been brought to user's operation.
Therefore, there remains a need for a MMC/SD interface-based system which simultaneously supports bulk storage and Ethernet communication.